modelCoolingMode
Information
This model implements a cooling mode controller for an air-cooled direct expansion (DX) cooling system with an airside economizer. This controller is based on a simplified differential dry-bulb temperature control strategy, as described in ASHRAE G36.
There are three cooling modes for this system: free cooling (FC) mode, partially mechanical cooling (PMC) mode and fully mechanical cooling (FMC) mode. The detailed switching logic is shown in the following:
The airside economizer is enabled when:
- Tout<Tret
The airside economizer is disabled when:
- Tout>Tret
The DX coil is enabled when:
- Tout>Tsup,set
The DX coil is disabled when:
- Tout>Tsup,set
where Tswi is the switching temperature, subscript set means set point, out means outdoor air, ret means return air, and sup means supply air. A deadband δT can be added to the above logics to avoid frequent switching.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Time | tWai | Waiting time, set to avoid frequent switching | |
| Modelica.Units.SI.TemperatureDifference | dT | 1.1 | Deadband |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealInput | TOutDryBul | Dry-bulb temperature of outdoor air | |
| Modelica.Blocks.Interfaces.RealInput | TRet | Return air temperature | |
| Modelica.Blocks.Interfaces.RealInput | TSupSet | Supply air temperature setpoint | |
| Modelica.Blocks.Interfaces.IntegerOutput | y | Cooling mode signal, integer value of Buildings.Applications.DataCenters.Examples.BaseClasses.Types.CoolingMode |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.StateGraph.Transition | con1 | Fire condition 1: free cooling to partially mechanical cooling | |
| Modelica.StateGraph.StepWithSignal | parMecCoo | Partial mechanical cooling mode | |
| Modelica.StateGraph.InitialStepWithSignal | freCoo | Free cooling mode | |
| Modelica.StateGraph.StepWithSignal | fulMecCoo | Fully mechanical cooling mode | |
| Modelica.StateGraph.Transition | con2 | Fire condition 2: partially mechanical cooling to fully mechanical cooling | |
| Modelica.StateGraph.Transition | con3 | Fire condition 3: fully mechanical cooling to partially mechanical cooling | |
| Modelica.StateGraph.Transition | con4 | Fire condition 4: partially mechanical cooling to free cooling | |
| Modelica.StateGraph.StateGraphRoot | stateGraphRoot | ||
| Modelica.Blocks.MathInteger.MultiSwitch | swi | Switch boolean signals to real signal |
Revisions
-
August 16, 2017 by Yangyang Fu:
First implementation.